Generally, while downmixing several audio objects to be a mono or stereo signal, parameters from the individual object signals can be extracted. These parameters can be used in a decoder of an audio signal, and positioning/panning of the individual sources can be controlled by user' selection.
However, in order to control each object signal, sources included in downmix need to be appropriately positioned or panned.
Moreover, in order to provide backward compatibility with a channel-oriented decoding scheme, an object parameter should be flexibly converted to a multi-channel parameter.